From 06c62d88088ea56c8775d008e7a6bed33b89c08c Mon Sep 17 00:00:00 2001
From: "Dr. Andrew Annex" <ama6fy@virginia.edu>
Date: Tue, 22 Oct 2024 12:58:34 -0700
Subject: [PATCH] Add CRS_to_urn (#752)

* adds CRS_to_urn function

* fix CRS expected type

* switch to using typing's version of Tuple

* format

* make the crs info function private

* update changelog

---------

Co-authored-by: vincentsarago <vincent.sarago@gmail.com>
---
 CHANGES.md         |  3 +++
 rio_tiler/utils.py | 24 +++++++++++++++++++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/CHANGES.md b/CHANGES.md
index b2a5ed08..62b32797 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,6 @@
+# 7.0.1 (2024-10-22)
+
+* Add `CRS_to_urn` method and update internals for `CRS_to_uri` (author @AndrewAnnex, https://github.com/cogeotiff/rio-tiler/pull/752)
 
 # 7.0.0 (2024-10-21)
 
diff --git a/rio_tiler/utils.py b/rio_tiler/utils.py
index 50c03d0c..098f0756 100644
--- a/rio_tiler/utils.py
+++ b/rio_tiler/utils.py
@@ -791,7 +791,7 @@ def cast_to_sequence(val: Optional[Any] = None) -> Sequence:
     return val
 
 
-def CRS_to_uri(crs: CRS) -> Optional[str]:
+def _CRS_authority_info(crs: CRS) -> Optional[Tuple[str, str, str]]:
     """Convert CRS to URI.
 
     Code adapted from https://github.com/developmentseed/morecantile/blob/1829fe12408e4a1feee7493308f3f02257ef4caf/morecantile/models.py#L148-L161
@@ -804,6 +804,28 @@ def CRS_to_uri(crs: CRS) -> Optional[str]:
         if "_" in authority:
             authority, version = authority.split("_")
 
+        return authority, version, code
+
+    return None
+
+
+def CRS_to_uri(crs: CRS) -> Optional[str]:
+    """Convert CRS to URI."""
+    if info := _CRS_authority_info(crs):
+        authority, version, code = info
+
         return f"http://www.opengis.net/def/crs/{authority}/{version}/{code}"
 
     return None
+
+
+def CRS_to_urn(crs: CRS) -> Optional[str]:
+    """Convert CRS to URN."""
+    if info := _CRS_authority_info(crs):
+        authority, version, code = info
+        if version == "0":
+            version = ""
+
+        return f"urn:ogc:def:crs:{authority}:{version}:{code}"
+
+    return None